لخّصلي

The Internet The Internet is a global system of interconnected computer networks.All communication via TELNET is carried out through a virtual device called Network Virtual Terminal (NVT).This Internet protocol suite is a conceptual model and a set of communications protocols, of which the foundational ones are the TCP and the IP. The Internet protocol suite is organized into four abstraction layers.TCP/IP is also known as the DoD (Department of Defense) model since the development of internetworking was originally funded by the United States Department of Defense through DARPA (Defense Advanced Research Projects Agency).The Internet is officially controlled by a suite or a stack of protocols called TCP/IP (Transmission Control Protocol/Internet Protocol).The IP protocol cannot account for any

losses or failures that stem from dynamic changes to routes between networks.TELNET (TErminal NETwork) is an Internet protocol that allows computer users to access computers from great distances (remote login). Through a particular user interface, the user is able to browse within the Web using a distinct URL (Uniform Resource Locator).IP provides no checking of the data in the datagram, so, while the header may be intact, the data may well be corrupted.Every email message issued from within the domain is first sent to the domain's mail server, which then directs the message to its destination.The message stays in the destination domain's mail server until the recipient requests to see their incoming mail.The local part specifies a special file, called the user mailbox, where all the incoming mail is stored for retrieval by the user agent.It establishes two connections between the linked devices: one for data transfer and one for control information (commands and responses).A client software application (Web browser) resides on the user's computer and is responsible for accessing information on the Web, and displaying it on the user's device.Numerous companies act as Internet Service Providers (ISPs) allowing customers to connect their domains to the Internet.IP simply builds datagrams (packets) and gives them to the link layer to send.

The Internet
The Internet is a global system of interconnected computer
networks. It can be conceived as a collection of domains, each of
which consists of a network or a smaller internet. Numerous
companies act as Internet Service Providers (ISPs) allowing
customers to connect their domains to the Internet. Each internet
is associated with a global addressing system that assigns a unique
address (IP address) to each computer in the system.
The Internet is officially controlled by a suite or a stack of
protocols called TCP/IP (Transmission Control Protocol/Internet
Protocol). This Internet protocol suite is a conceptual model and a
set of communications protocols, of which the foundational ones
are the TCP and the IP. The Internet protocol suite is organized into
four abstraction layers. From lowest to highest, the layers are the
link layer, the internet layer, the transport layer, and the
application layer. TCP/IP is also known as the DoD (Department of
Defense) model since the development of internetworking was
originally funded by the United States Department of Defense
through DARPA (Defense Advanced Research Projects Agency).
The Internet Protocol (IP) is not designed to be a reliable
protocol; it is a best-effort delivery service. IP simply builds
datagrams (packets) and gives them to the link layer to send. The
only error checking that is performed by the IP is through
checksum. The checksum is a mathematical function of the bits in
the header. IP provides no checking of the data in the datagram,
so, while the header may be intact, the data may well be
corrupted. Also, it is possible that a data link, router, or computer
fails at a time when datagrams are transmitted, resulting in the
loss of those datagrams. Additionally, datagrams may arrive out of
sequence or duplicated. The IP protocol cannot account for any

losses or failures that stem from dynamic changes to routes
between networks.

Networking applications
One of the most popular applications on the Internet today is
electronic mail (email). Messages are transferred among Internet
users through the support of a protocol called Simple Mail Transfer
Protocol (SMTP). Each domain’s local authority designates a
particular machine (mail server) within its domain to handle the
domain’s email activities. Every email message issued from within
the domain is first sent to the domain’s mail server, which then
directs the message to its destination. The message stays in the
destination domain’s mail server until the recipient requests to see
their incoming mail. SMTP uses a unique addressing system that
consists of two parts: a local part and a domain name separated by
an @ sign. The local part specifies a special file, called the user
mailbox, where all the incoming mail is stored for retrieval by the
user agent. The domain name illustrates the computer which
implements the specific SMTP server.
One standard protocol on the Internet for transferring files such as
documents, photographs, or other encoded data, is the File
Transfer Protocol (FTP). FTP is designed to deal with problems
such as different coding systems or diverse file formats. It
establishes two connections between the linked devices: one for
data transfer and one for control information (commands and
responses). The control connection has to be present throughout
the FTP session, while the data connection is present only when
there is data to be transferred.
TELNET (TErminal NETwork) is an Internet protocol that allows
computer users to access computers from great distances (remote
login). All communication via TELNET is carried out through a
virtual device called Network Virtual Terminal (NVT).

The World Wide Web (WWW), or the Web, is an application that
allows multimedia information to be shared across the Internet. It
is based on the concept of hypertext, which is a document
containing links (hyperlinks) to other documents. A hypertext
document is called a page, and a collection of closely related pages
forms a Web site. HTTP (Hypertext Transfer Protocol) is the
client-server program that is used so as to access and transfer
documents on the Web. A client software application (Web
browser) resides on the user’s computer and is responsible for
accessing information on the Web, and displaying it on the user’s
device. Through a particular user interface, the user is able to
browse within the Web using a distinct URL (Uniform Resource
Locator).